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So when he slowed it down before, it got hotter inside,reg's were sweating but the discharge temp was lower, did he goof up not adjusting charge?

I understand i'm not gonna get 2k from the unit, just that is what the "high" speed rating for the 5ton air handler unit has for the blower. As for the water, it has to go 35" from the coil then up 18" [ it's a 22x18x35 mixing chamber]to even get to where the trunk is mounted, still think that's part of it, even tho it didnt help slowing the fan down?

Originally Posted by beenthere

More like your pulling fresh air into the return. Then undersized.
Undersized tends to remove more humidity, but not cool the house as well. Oversized tends to cool the house too quickly, and not remove humidity.

That's why i keep getting told to go with the bigger unit.
I metal sealed myself the new intake plenium that he added, and even the coners of the handler, but will giva look at the new ring we mounted for the 16" flex return from my floor intake.

When i had the 3rd tech out he told me that even though it's not "ideal" sized for 4 ton, it's got enough fan and intake to move the air thru. He felt the flow from all the registers and was suprised thet they flowed very well. So on that aspect, I'm moving x amount of air now, how is having a coil box that is slightly bigger than now not gonna be hindered by the current trunk size, and even if we have to "slow" the fan back down?

Remember were talking of an 1800sf poorly insulated 1 and 1/2 story house with a "high" heatload, so rule of thumb[1cfm per ft] is 1800cfm,with at least a 4 ton unit correct?
6 rooms of the house get the full brunt of the sun from mid afternoon on, and its the whole 1&1/2 side that's catching it!!
Also has 6 full size windows, 2, 1/2 windows, ans 2 French doors, but they are double glass I changed out last summer.

To actually be comftrouble[ sure wasnt with the old 3.5 ton, and still not now!!!!! Temp rise is at least 4*+ from 400pm thru 8pm, even with unit running.

Unless thers a miricale cure lurking, I dont want to keep messing around with what seems to be a "not ideal" setup that we now have.
We expect to have an AC that will cool the house, far better than before, and better than what we have now.

House is a 1985 1.5 story aprox 1750sf, and has not so good windows, and no vapor sheeting, and not too good batten insulation. 2 B/R up with 1 full bath[300sf+/-], so only 3 vents up there, all under a 44square roof.

Not so good windows, as in single pane, aluminum frame jobs, I imagine. No vapor sheeting...do you mean there never was a layer of plastic placed on the inside of the stud walls before the drywall went on? If that's the case, you don't want that, anyway. If you mean the exterior sheathing of the house (the plywood/chipboard that went over the studs before the siding or brick was put on) has no house wrap or tar paper...not so good.

Why am I talking about construction materials when you're talking about an a/c problem? Because the two are intrinsically related. You cannot address an interior comfort issue without looking at both the house you are trying to heat or cool, and the equipment tasked with heating or cooling.

Yes, it sounds like you have serious design and performance issues with your current a/c system. But it also sounds like your house envelope is an energy sucking hog that needs considerable improvement, so your a/c equipment is not constantly fighting a losing battle to keep you comfortable.

Gotta run...I'll post more thoughts about your current situation after awhile.

You need someone that knows what they are doing.
A load calc should have been done, instead of guessing and using bad rules of thumb.
Your 16" flex is not big enough for 4 tons of A/C.
Your supplies are already under sized for 3.5 ton.
Increasing size to 4 tons with your current duct system could make things even worse.

Look in the phone book for companies that are NCI certified. Or go to there website and look for contractors in your area.

The museum I take care of, has to be very carefull with their humidity in both summer and winter.
The inlays get loose if its too dry, and the wood pushes apart with too much humidity.
Some of their displays of Grandfather clocks, and 200 year old chests, and hutches are in excess of $100,000.00. So they are picky about their humidity.

You take care of a museum too, eh? Guess the main difference is I do it full time.

We keep a pretty tight environmental control for similar reasons as to what you listed above, with the emphasis being toward paintings, works on paper, and photographs. I'm either humidifying or dehumidifying, or the way some of our equipment is set up...both.

Sweating ducts are indicative of several things. First of all, if your ducts are sheetmetal and are running through a crawl space or basement, the ducts are likely uninsulated, and the crawl space or basement has high humidity. If you do not have any ongoing process to keep the humidity under control in the basement/crawl space, it's likely a good amount of this moisture is seeping into your home, overwhelming your a/c system's ability to do the job of both extracting moisture AND keeping you cool. With water pouring out of your condensate drain (setting aside for the moment the duct sizing issues mentioned by other posters), that can indicate a high amount of moisture being passed over the cooling coil, which lowers the ability of your a/c system to reduce the actual temperature of the house.

So...in addition to the actual duct sizing concerns already raised, you would be well served to add to your focus emphasis on indoor humidity control, particularly in your basement/crawl space. You should also have the entire duct system checked for leakage, especially on intake/return side. If you are sucking moisture out of your basement/crawl space and into the a/c intake, you'll never get a handle on keeping your living areas comfortable.

Yea, and I have to make do with equipment that is residential, and not designed for the way they use it.
Makes it tough some times.

I think there must be some folks in this world who believe you can cool and control any indoor environment with a resi split system. I could only imagine 44 five ton split systems trying to do the job of one of my chillers and eight air handlers do 24/7/365. You couldn't stand to be in the place....the roar of 44 air handlers and 44 compressors outside would be unbearable. Not to mention curators constantly at my door while I fight a losing battle of hoping to control a gallery environment with DX, constant velocity air handlers.

My mechanicals are not the most ideal for a museum, but we manage decently. It would be laughable with residential split system equipment.

Maybe Teddy Bear will visit with you too. It seems to me you need to encapsulate your crawlspace and seal your ducts first. I think installing a bigger unit would be a big mistake.

You also need someone to MEASURE your air flow when they set the fan speed. They can do that with a flow hood or test static pressure. Right now they are guessing, and that is no way to design a system.

Now before he arrived I contacted an "online" store and the tech there are VERY helpful! They said thed love to sell me a unit, but want to make sure that what I really need.
After describlng the "symptoms, I gave them the measurements of duct.

Online tech Stated I need to run a pair of 6" or an 8" duct from trunk#1 to "balance" system for 1400cfm total flow.

This is what the installer sayed tonite:

Installer stated he dont do "model J", that the calcs are way too oversized many times, mainly from "R value" guessing.

Stated he wants to measure the ductwork so he can calculate what the flow rate is. {even though I told him I had all that right here for him, including some phone calculations for the flow} That were taken from a "Duct-A-lator"

"No I got to do that himself, see you the next Monday eve."

Now then he said he dont have a "flow" meter, that he can calculate that from the "duct" sizes.

Said that the "upstairs" is taking all the air since the duct is not "reduced" anywhere in trunk #2.

"Need to redu the entire duct, so that the "reductions" are in place to keep static pressure proper, [but dont have a flow meter?]

Originally Posted by Kevin O'Neill

You also need someone to MEASURE your air flow when they set the fan speed. They can do that with a flow hood or test static pressure. Right now they are guessing, and that is no way to design a system.

Now before he arrived I contacted an "online" store and the tech there are VERY helpful! They said thed love to sell me a unit, but want to make sure that what I really need.
After describlng the "symptoms, I gave them the measurements of duct.

Stated I need to run a pair of 6" or 1 8" duct from trunk#1 to "balance system for 1400cfm total flow.

Installer stated he dont do "model J", that the calcs are way too oversized many times, mainly from "R value" guessing.

Stated he wants to measure the ductwork so he can calculate what the flow rate is. {even though I told him I had all that right here for him, including some phone calculations for the flow}

"No I got to do that himself, see you the next Monday eve."

Now then he said he dont have a "flow" meter, that he can calculate that from the "duct" sizes.

Said that the "upstairs" is taking all the air since the duct is not "reduced" anywhere in trunk #2.

"Need to redu the entire duct, so that the "reductions" are in place to keep static pressure proper, [but dont have a flow meter?]

What 'di miss???

I'm sorry, but you have way too much wrong information being tossed around and way too much irrelevant data. You need to get an HVAC professional who knows what they are doing and STOP playing pseudo engineering games. There is not much data that you have posted that makes much sense. It's like reading notes from someone who is reading a technical manual but has no idea what it is they are reading.

DO WHAT I TOLD YOU TO DO MANY POSTS AGO! HAVE THE AIR FLOW ADJUSTED TO BELOW 1400 CFM AND THEN HAVE THE REFRIGERANT CHARGE PROPERLY ADJUSTED TO THE MANUFACTURER'S REQUIRED SUPERHEAT AND SUBCOOLING.

All you are doing is screwing your equipment up and putting a boatload of damaging moisture into your home. Stop it!